William j



w. J. HERDMAN.

HIGH FREQUENCY DISCHARGE APPARATUS.

APPLICATION FILED 1AN.26.191B.

1 23,472. Patented Dec. 2,1919.

LAT;

UNITED STATES" PATENT OFFICE,

7 WILLIAM J'.'HERDMAN, 0F TORONTO, ONTARIO, CANADA.

HIGH-FREQUENCY DISCHARGE APPARATUS.

To all whom it may concern: I Be it known that I, WILLIAM J HERDMAN, a citizen of the United States of America, and a resident of Toronto, county of York, and Province of Ontario, Canada, have invented a new and useful, Improvement in High-Frequency Discharge Apparatus, of which the following is a specification.

My invention relates to apparatus for producing electric currents of hi h frequency and tension and pertains specifically to that class of such apparatus which finds its chief use in electrotherapeutics.

The principal object of my invention consists in producing a high frequency generator in which the intensity and pressure of the electrical dischargemay be varied at will without varying the frequency or rate of oscillation of such discharge.

In my novel and improved device I employ means to render the operating current intermittent and thereafter transform the interrupted operating current into a high potential current oscillating at extremely high frequency. I further provide means for adjusting the pressure and intensity of this high frequency current without altering in I any way its rate of oscillation. In this way.

the strength of the discharge atthe elec trodes may be adjusted to a value suitable to the sensitiveness of the patient or of the portion of the body to which it is to be applied and the frequency of the oscillation be maintained at a high valuein order that the pathological effects of the current. may

be retained and the disagreeable physical effects of low frequency current, such as jarring of the muscles and sensory nerves, may be eliminated.

the drawing which accompanies and forms a part of this specification I have illustrated. diagrammatically the apparatus and electrical circuits of my complete device.

Referring now particularly to the drawing, I employ'an electromagnet comprising a core of-soft iron wires 10 and a winding 11 and provided with a rheotome comprising the vibrating member 16 (connected. through conductor 29 with binding post 14:), armature 17, fixed contact support 19 and adjustable contact screw v18. One terminal of the winding 11 is connected to the fixed contact support 19. The other terminal of the winding 11 is connected as shown to the binding post 12 and the action of the electromagnet 10-11 in rapidly vibratmg Specification of Letters Patent.

Patented Dec. 2, 1919.

Application filed January 26, 1918. Serial No. 213,982.

the rheotome when the binding posts 12 and 14 are connected to any source of current supply isone well known in the art and needs no further explanation.

I provide a static transformer comprising the primary winding 24 and the secadjustable non-inductive resistance 25, the

movable member of which is connected through conductor 26 with the fixed element 19 of the rheotome. The condenser 20, primary of the static transformer and adjustable resistance 25 are therefore all connected in series and in a normally closed circuit including the two elements of the rheotome. The terminals of the secondary 23 of the static transformer are connected to suitable binding posts as 21 and 22 to which electrodes may be attached for utilizing the high frequency high tension current generated in the static transformer for medical purposes.

It will be observed that as the rheotome is vibrated by the electromagnet 1011 the condenser 20 is alternately charged and discharged, for as the contact between the movable member 16 and the contact screw 18 is broken a rush of current at a very high pressure, due to the counter electromotive force of the electromagnet '10-11, surges through the non-inductive resistance 25, primary 24 of the static transformer andcondenser 20, to charge the condenser to the potential of the counter electromotive force of the electromagnet 1011, then as the contact between the contact screw 18 and the discharge current alternates at an excessively high frequency, and thus a high frequency high'tension current is obtained at the binding posts 21 and 22 from the secondary 23 f the static transformer. The discharge ob ained is however of one predetermined strength-or intensity and-in the therapeutic use of such devices it is impera-- tive that the intensity of the discharge be varied through extremely wide limits to suit the patient or the various portions of the human body to which it is to be, applied. Itis to this end that my invention is directed, and my improvement resides in the apparatus, for as a small resistance is introduced into the circuit containing the condenser 20 and the primary 24 of the static' transformer the peaks of the condenser discharge are flattenedwithout appreciably diminishing the rate of oscillation of the condenser discharge and thus as resistance is introduced or abstracted by moving the movablemember of the adjustable resistance 25 the intensity of the discharge is weakened or intensified to suit the subject being-operated on without varying the frequency of the discharge current. Further, it will be noted that as the current passin through the electromagnet 1011 is not 0 anged in value by the operation of the adjustable resistance, the rheotome always operates at.

uniform speed and hence the condenser is charged and discharged at a substantially uniform rate at all times.

From the foregoing it will be readily observed that with my novel and im roved device consistin of few and sirnp e parts I am able to a just through extremely wide limits the strength of the discharge current obtained from the binding posts 21 and 22 Without in any way appreciably afl'ect ing the rate at which the condenser dis charge takes place or the rate at which the rheotome is operated, and consequently I am able to proportion the strength of the discharge to the sensitiveness of that portion of the body being "operated on without losing any of the beneficial effects of the discharge which are so largely dependent on -maintaining the frequency at a high value. l

IIaving thus fully and completely described my invention what I claim as new and desire to secure by United States Letters Patent is as followsia source of current, an electromagnet, a current interrupting device operated by said electromagnet, and a static transformer, adjustable resistance and condenser connected in series with each other and to the elements of said current interrupting device.

a. In a deviceof the character described, an electric switch comprising a movable member and a stationary member, an electr-omagnet for operatin said switch, and a static transformer, ad ustable non-inductive resistance and condenser connected in series with each other and to said movable member and said stationary member of said switch.

Signed by-me at Toronto, county of York, and Province of Ontario, in the presence of two Witnesses.

' WILLIAM J. HERDMAN.

Witnesses:

S. B. CAMPBELL, L. NEUsoMn 

